1. Field of the Invention
This invention generally relates to a clutch disk assembly. More specifically, the present invention relates a clutch disk assembly which has a plurality of cushioning plates annularly disposed about its outer peripheral portion.
2. Background Information
A clutch disk assembly for a clutch of a car typically includes a pair of disk-like input plates, an output hub having a flange on its outer circumference, and an elastic member disposed between the input plates and the flange of the output plate as to allow limited relative rotation. On the outer peripheral portion of the pair of input plates, a friction connecting part is secured. The friction connecting part has a plurality of cushioning plates and two pieces of friction facings.
Several cushioning plates are annularly disposed along the outer peripheral portion of the clutch disk assembly, and a friction facing is disposed on either side of a group of cushioning plates in an axial direction. Each of the cushioning plates includes an installation part connected to a clutch plate (one of input plates) by rivets, for example, and an elastic part disposed between two pieces of friction facings. The elastic part has a wavy shape and can deform flexibly between the two friction facings.
In a clutch disk assembly with the above-mentioned structure, i.e., with a couple of input plates, the clutch plate and the retaining plate are fixedly coupled to each other at a plurality of positions of their outer circumferences by a plurality of connecting pins (stop pins). The connecting pins (stop pins) extend in an axial direction between the clutch plate and the retaining plate. The connecting pins pass through cutouts formed at the outer circumference of an output hub flange. When the input plate rotates relatively against the output flange by a predetermined angle, the connecting pins prevent the input plate from rotating or twisting more than the angle by the connecting pins engaging the edges of the cutouts.
In the above-mentioned conventional structure, the connecting pins are located very close to the rivets, which fixedly couple the installation parts of the cushioning plates to the clutch plate. In particular, the end part of the connecting pins are inlaid in installation holes of the clutch plate, and are fixedly coupled to the clutch plate by caulking between the installation parts of two adjacent cushioning plates in a circular direction, and inwardly from them in a radial direction.
In such a structure, since the caulking of the connecting pins reinforces the circumferences of the installation holes of the clutch plate, the circumferences are rigid and hard to deform even if it receives a bending stress in an axial direction of the clutch. On the other hand, in connecting or disconnecting the clutch, the above-mentioned elastic parts of the cushioning plates are deformed and ease the shock. Corresponding to the deformation, the installation parts of the cushioning plates are going to be deformed in an axial direction. However, the circumferences of the installation holes of the clutch plate are reinforced as described above. Therefore, when the installation parts of the cushioning plates are deformed, the clutch plate and the rivets near the installation parts are not deformed or inclined according to the deformation of the installation parts. As a result, a large local stress occurs at the circumferences of the rivets of the installation parts, which may possibly result in a crack occurring around one or more of the rivets.
It is possible to overcome the above-mentioned risk, when the connecting pins are far apart from the installation parts inward in a radial direction. In that case, the radial distance between the connecting pins and the center of the disk is short. Therefore, when the connecting pins contact the edge of the cutouts of the flange, the stress applied to the stop pins and the edges of the cutouts increases. This arrangement requires the input plate or the output flange to be strengthened.
In view of the above, there exists a need for a clutch disk assembly which overcomes the above-mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.